Stroke-changing mechanism



Jan. 1925. 1,523,515

M. CLODFELTER s'rnoxn CHANGING MECHANISM Filed Ju y 15, 54 2 Shuts-Shoat l Patented Jan. 20, 1925,

PATENT ()FFICE.

MAYO GLODFELTLER, Q3? CHICAGO, ILLINOIS.

STROKE-CHANGING- MECHANISM.

Application filed July 15, 1524..

To all whom it may concern Be it known that I, Maro Gnonmnnnu, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in StrokeChanging Mechanism, of which the following is a specification.

This invention relates to mechanism for varying the stroke of engines, particularly internal combustion engines.

An important object of the invention is to provide means in connection with engines for varying the stroke thereof according to the number of revolutions per minute.

A further object ofthe invention is the provision of a mechanism of this character which will operate automatically and materially increase the efficiency of the engine.

A still further object of the invention is the provision of a mechanism of this character which is comparatively simple in e0nstruction, durable and efilcient for this purpose.

Other objects and advantages of this invention will be apparent during the course of the following description.

In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate like parts throughout the same:

Figure 1 is a plan view showing my improved device mounted upon the crank shaft,

Figure 2 is a side elevation of the same,

Figure 3 is a side elevation taken on the line 33 of Figure 2,

Figure 4 is a vertical sectional view taken on the linear- 1 of Figure 2,

Figure 5 is a transverse sectional view taken on the line 5 5 of Figure 2, and

Figure 6 is an enlarged sectional view showing the construction of the stop mechanism.

As it is Well understood by those familiar with devices of this character, internal combustion engines when traveling at a high rate of speed lose much of their efficiency due to the small amount of explosive gas. fed into the cylinders and a corresponding loss in compression. It is to offset this loss in efiiciency that my improved mechanism is employed, this mechanism being adapted to automatically lengthenthe stroke of the Serial N0. 726,227.

engine and compensate for the loss of power occasioned by the increased speed thereof.

in the drawings, wherein for the purpose of illustration shown the preferred embodiment of my invention, the numeral 10 generally indicates a conventional type of crank shaft comprising a comparatively long crank arm 11, a shorter crank arm 11 and crank pins 12. I have also shown a. conventional type of connecting rod 13 mounted upon the pin positioned between the long and short arms.

Referring more particularly to my improved device, I provide an eccentric 14: n'eferably formed of two sections having a suitable opening formed therein for engagement with the crank pin, these eccentric sections being securely retained upon the crank shaft by means of the connecting rod bearing cap. On one extremity of the sccentric is mounted a toothed gear 15 this gear being rigidly secured to the extremity of the eccentric and adapted to rotate the same about the crank pin.

A. Teha'ped groove 16 is formed on the outer face of the crank arm 11, this groove extending very' nearly the entire length of the crank arm in the center thereof.

A sliding block member 17 having a T- shaped bar formed on one face thereof and adapted to engage the groove 16 formed in the crank arm is adapted. to reciprocate on the outer face of the arm. Formed on the narrow side of the block 17 near the lower extremity thereof is a toothed rack 19, this rack being provided with teeth suitable to engage the teeth formed on the gear 15, the rack being so positioned as to engage the teeth in order to impart rotary movement to the gear. The outer face of the block 17 is also provided with a T-shaped groove 20, a rectangular stop lug 21 being positioned in the lower portion of this groove to limit movement of a member to be mounted therein.

A rectangular weight member 22 is slidably mounted on the outer surface of the block 17, this weight member having a T- shaped bar formed on the inner face thereof for engagement with the slot 20 formed on the outer face of the block 17. It is obvious that the weight 22 is slidably mounted upon the block 17 and this block is likewise slidably mounted upon the crank arm, the do\rnv-.'ard movement of the weight 22 being limited by the lug:- 21, while movement ot the block ll limited by the lower lug 22 and ti e upper extremity of the groove 16.

As it is necessary to provide means tor locking the weight in position after move ment thereof, .i provide a pair of sliding dowel pins 2- slidably mounted in the sliding block 17. These pins are mounted in circular grooves 524- formed in the block 1?, the pins comprising a cylindrical shank 23 having an enlarged circular shoulder it formed on the lower extreinity while the upper extremity carries a semicircular knob 27 threadedly mounted upon the upper e)-:- tremity t he shank and adapted to nor nally extend above the block. A guide collar 28 is formed in the groove 2%, the central portion thereot being provided with a circular opening adapted to receive the shank 95 and permit the same to slide therein. A coiled spring 29 is positioned about the shank 25 liietween the collar 28 and the upper knob 27, this spring having a tendency to torce the pin in the raised position as clearly shown in Figure 6. A suitable circular recess 30 is formed in the outer "face of the crank. this recess being adapted to receive the shoulder 26 on the pin when the same in the locked position. In order to automatically throw the pin in engagement with the crank arm the sliding weight 22 is provided with arcuate grooves 31 formed near the upper and lower extremities thereof and adapted to engage the knob 27 formed on the upper portion of the pin members. It is obvious that movement of the weight will cause the arcuate grove 31 to slide over the knob 27 on the pin and force the same downwardly into the recesses formed in the crank arm thereby retaining the sliding block I? rigidly in position.

in order to retain the sliding weight and block members in their upper position. that is. to reduce the stroke while the engine is operating at a con'iparathrely low speed, I provide a pair or" coiled compression springs 32 and 3 these springs being mounted in the T-shaped grooves termed in the outer tace oi" the sliding block 17 and the crank arm respectively, these springs "bearing against the lower portions of the weight and block and torcing the same to the upper position.

in operation, as the speed of the engine increases beyond a certain P. P. M. at which the springs are set, the sliding weight 22 will. be thrown by centrifugal force towards the outer extremity of the crank arm, this movement releasing the upper pin and causing similar movement of the block member 17. ."Vhenthe lower dowel pin aligns with the lower recess 30 formed in the crank arm the weight member 22 will .t'orcc the pin into this recess and lock the same therein causing the sliding block member and weight to retain these positions until the sieed ot the motor reduced. It is further to be noted that this movement of the sliding block 17 will cause similar io-rement of the rack 10 termed thereon, hus rotating the toothed gear 15 carrying he eccentric. As the eccentric is rotated the crank pin a corresponding inin sroke length will result thus accomplishing the purpose intended. its the speed ot the engine is lowered the compres sion s rings 32 and 33 will return the iglzt member 22 and sliding block 17 to their normal position with a corresponding reduction in stroke length.

it to be understood that the form o't my invention herewith shown and described is to be taken as the preferred example of the same, and that various changes as to the shape, size and arrangement of parts my be resorted to without departing from the spirit of the invention, or the scope of the subjoined claims.

Having thus described my invention, I claim:

1. A device of the character described comprising a sliding block member having a T-shaped bar formed thereon, a sliding membu' slidably mounted within a suitable groove formed in the sliding block member. a toothed rack member formed on the side of the said sliding block, means for normally retaining the said sliding block and weight member in a raised position, and means for locking the said sliding block.

2. A device of the character described comprising a sliding block member having a groove formed on one side thereof, a T-shaped bar formed on the opposite side of the said block member, a toothed rack formed on one extremity 01 the said block member, a sliding weight member having a T-shaped bar formed on one side adapted to slidably move within'the groove formed within the said block member, spring'members adapted to normally retain the said block and weight members in a set position, and sliding pin members adapted to retain the said block in locked position.

in combination with an internal combustion engine crank shaft, of an eccentric mounted on the pin of the said crank shaft, a gear mounted on one extremity of the said eccentric, a sliding block member mounted on one side of the crank shaft arm, a toothed rack adapted to rotate the eccentric mounted on one side of the sliding block member, a weight member slid-ably mounted on the outer face of the said block, and means for normally retaining the said sliding block in a certain position.

t. In combination with an internal combustion engine, and a crank shaft mounted on the said engine, of an eccentric rotatably mounted on the pin of the said crank shaft, a toothed gear mounted on one end of the said eccentric, a sliding block member having a projecting; bar formed on one side adapted to move in a suitable groove formed in the crank shaft arm, a toothed rack member formed on one extremity of the said block, a slidable weight having a projection formed on one side thereof adapted to slide within a suitable groove formed in the said block member, coiled spring members mounted in the grooves and adapted to retain the said slidable members in an inope 'ative position, and a plurality of slidable pin members mounted in the slidable block for locking the same in position.

5. In combination with an internal combustion engine, and a crank shaft rotatably mounted in the said engine, of an eccentric formed of two sections mounted on the pin of the said crank shaft, a toothed gear formed on one extremity of the said eecentric, a slidable block member having a T-shaped bar formed on one side thereof and adapted to slide in a suitable groove formed in the crank shaft arm, a toothed rack formed on the side of the said sliding block member and adapted to mesh with the said toothed gear member, a sliding weight member having a T-shaped bar formed on one face thereof and adapted to slide in a suitable groove formed in the face of the block member, a pair of coiled compression springs secured in the said grooves adapted to normally retain the sliding block and weight members near the inner extremity of the said crank shaft arm, and a plurality of dowel pins slidably mounted within suitable bores formed in the side of the block member for locking the same in position.

I11 testimony whereof, I have aflixed my signature in the presence of two witnesses.

MAYO CLODFELTER. Witnesses C. P. JAGER, CLARENCE A. LAMBERT. 

